Today I will (finally) finish my comments on Tom Vanderbilt’s book, Traffic. He observes that drivers travelling 50 miles per hour are 25 times more likely to die than those driving at 25 miles per hour (p. 210).

This fact, which is well documented, has several implications for how supervising adults should deal with teen drivers. First, obviously, when you act like an air traffic controller and work with your new drivers to prepare a “flight plan” for each drive, and you consider the route, you should evaluate the likely, average speed of cars on the roads that will be taken on that drive. For new drivers, in general, the escalating risks of high speeds warn against allowing them to drive on a limited access highways with high posted speed limits (and minimums) such as Interstates, or avoiding such roads as much as possible. (However, it is important to note that divided highways, with multiple lanes travelling in the same direction and separated from opposing traffic by a barrier, are safer than highways in which the only separation between traffic directions is a pavement marking.) Second is to counsel teens, where possible, to avoid roads on which they will be able to drive at higher speeds, such as long straightaways with relatively little traffic. Conversely, though we might think that having teen drivers use congested or heavily-trafficked areas is more dangerous (and nerve-wracking) than more open roads, Vanderbilt’s observation tells us that there is actually less risk wherever traffic, whether due to speed limits or congestion, operates at lower speeds.

It is important to note that Vanderbilt’s caution is not a linear equation. Starting at 25 MPH, twice the speed increases the risk by 25 times. In other words, once a driver gets beyond the speed of a quiet residential street, the risk of a serious injury or fatality rises quickly. We should also bear in mind why higher speeds are much riskier, especially for teens: circumstances change more rapidly, there is more for drivers to keep track of, and new drivers in particular have slower reactions because they are less skilled at looking down the road to see situations developing in the distance, and their reactions to unexpected developments and safety hazards are uncertain at best.

To summarize, an important guideline for adults supervising teen drivers, especially brand new ones, is to avoid the higher speed roads, because 50 is much more dangerous than 25.

Last week I attended (and spoke at) the Lifesavers Conference, the annual meeting of the national traffic safety community, and as usual I came away with new ideas for blog posts. Let me start with a new thought about teen driving agreements (see my model agreement in English and Spanish, on the landing page of this blog).

At Lifesavers I was part of a panel with Violet Marrero of the New Jersey Division of Highway Traffic Safety. She explained an innovative and effective program called Share the Keys (which I will discuss in a later post). Violet reviewed my model teen driving agreement and suggested that compliance with teen driving agreements is improved if some form of incentive or reward is built into the agreement. This makes perfect sense; I appreciate the suggestion, and pass it along with some thoughts and caveats about how to implement it.

The first question is: When has a teen driver “complied” with a Teen Driving Agreement? As noted in a recent post, we should not measure a teen driver’s success, or compliance with an agreement, based on him or her not having gotten into a crash and not having received a ticket from law enforcement. These are not measures of compliance. Teen drivers are supposed to avoid crashes and not get tickets, and doing so is not extraordinary effort. So what is an appropriate measure of and procedure for determining compliance? My suggestion is to pick a time frame — if the term of the agreement is at least one year (as my model suggests), then perhaps every three months, the supervising adult and teen can sit down and go through the agreement section by section, and if the teen has willingly followed each and every section, and has no violations, that would be compliance. (Yes, the supervising adult will need to rely on the teen’s say-so for several items, but I don’t think that is unusual for parenting a teen.) Put another, way, if a teen has been dragged kicking and screaming into compliance, or if there is some significant doubt (such as denial of a report of misconduct from a reliable source), then that should not qualify as compliance.

What type of reward is appropriate? The obvious one is the supervising adult paying for a tank of gas or some driving-related expense. This can be written into the “Expenses” paragraph of the agreement. The supervising adult should be sure that taking over a particular expense does not undermine one of the purposes of the agreement, which is to make the teen driver realize the costs of driving. The expense paid for should be modest and on a one-time basis. The reward should not be substantial (such as buying a teen a car, or helping buy one). I don’t think the reward should involve a non-driving item such as household chores (and my model recommends keeping these separate). Finally, by no means should the reward ever be permission to violate state law or a safety provision of the teen driving agreement, such as allowing the teen to carry illegal passengers or stay out past the legal curfew.

So, with these understandings and limits, rewarding teen drivers who willingly and fully live up to the terms of teen driving agreements is an appropriate incentive.

The Lifesavers Conference is the annual meeting of the national traffic safety community. This year, it will take place in Orlando from June 14-16. The conference features several “tracks” - seminar series — including on distracted driving and teen driving. I am thrilled to have been asked by the National Organizations for Youth Safety (NOYS, www.noys.org) to represent them on a panel entitled “How To Engage Parents In Their Teen’s Driving,” and to talk about NOYS’s UnderYourInfluence website, www.underyourinfluence.org. I will also be saying a few words about teen driver agreements and my new model, featured on the landing page of this blog. I will be speaking on Saturday June 16 at 9 AM. A copy of the handout for my presentation is here.